Hidden in a courtyard next to Cynthia Rowley's Montauk boutique is this "makeshift" summer stand, a spinoff from chef David Chang's Momofuku empire. The sought-after stuff: pastry chef Christina Tosi's salty-sweet compost cookies, made with oatmeal, pretzels and potato chips, as well as her sugar-intense crack pie, to be washed down with the curiously compelling cereal milk slushie, made with milk that's been steeped with cold cereal. Counter service and outdoor seating at benches with umbrellas.